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Query: UMLS:C0004134 (ataxia)
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Angelman syndrome (AS) is a neurogenetic disorder characterized by severe mental retardation, ataxia, seizures, EEG abnormalities and bouts of inappropriate laughter. AS individuals fail to inherit a normal active maternal copy of ubiquitin protein ligase E3A (UBE3A). UBE3A is subject to genomic imprinting, with predominant transcription of the maternal allele in brain. The known genetic causes of AS are maternal deletion of chromosome 15q11-q13, paternal chromosome 15 uniparental disomy, UBE3A mutation and an abnormality of the imprinting process, termed imprinting defect. There remain major questions concerning the molecular pathogenesis of AS, including: 1) the mechanisms underlying the imprinting defect class of AS, 2) the identity of proteins targeted by UBE3A, 3) the role of a noncoding antisense transcript in regulating UBE3A imprinting and 4) the contribution of other genes such as methyl-binding CpG-binding protein 2 and gamma-aminobutyric acid A receptor, subunit beta3 to the AS phenotype.
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PMID:Molecular epigenetics of Angelman syndrome. 1734 96

Angelman syndrome is a neurodevelopmental disorder characterized by mental retardation, severe speech disorder, facial dysmorphism, secondary microcephaly, ataxia, seizures, and abnormal behaviors such as easily provoked laughter. It is most frequently caused by a de novo maternal deletion of chromosome 15q11-q13 (about 70-90%), but can also be caused by paternal uniparental disomy of chromosome 15q11-q13 (3-7%), an imprinting defect (2-4%) or in mutations in the ubiquitin protein ligase E3A gene UBE3A mostly leading to frame shift mutation. In addition, for patients with overlapping clinical features (Angelman-like syndrome), mutations in methyl-CpG binding protein 2 gene MECP2 and cyclin-dependent kinase-like 5 gene CDKL5 as well as a microdeletion of 2q23.1 including the methyl-CpG binding domain protein 5 gene MBD5 have been described. Here, we describe a patient who carries a de novo 5Mb-deletion of chromosome 15q11.2-q13.1 known to be associated with Angelman syndrome and a further, maternally inherited deletion 2q21.3 (~364kb) of unknown significance. In addition to classic features of Angelman syndrome, she presented with severe infections in the first year of life, a symptom that has not been described in patients with Angelman syndrome. The 15q11.2-q13.1 deletion contains genes critical for Prader-Willi syndrome, the Angelman syndrome causing genes UBE3A and ATP10A/C, and several non-imprinted genes: GABRB3 and GABRA5 (both encoding subunits of GABA A receptor), GOLGA6L2, HERC2 and OCA2 (associated with oculocutaneous albinism II). The deletion 2q21.3 includes exons of the genes RAB3GAP1 (associated with Warburg Micro syndrome) and ZRANB3 (not disease-associated). Despite the normal phenotype of the mother, the relevance of the 2q21.3 microdeletion for the phenotype of the patient cannot be excluded, and further case reports will need to address this point.
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PMID:Angelman syndrome and severe infections in a patient with de novo 15q11.2-q13.1 deletion and maternally inherited 2q21.3 microdeletion. 2312 39

"Angelman syndrome" (AS) is a neurodevelopmental disorder whose main features are intellectual disability, lack of speech, seizures, and a characteristic behavioral profile. The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water. Microcephaly and subtle dysmorphic features, as well as ataxia and other movement disturbances, are additional features seen in most affected individuals. AS is due to deficient expression of the ubiquitin protein ligase E3A (UBE3A) gene, which displays paternal imprinting. There are four molecular classes of AS, and some genotype-phenotype correlations have emerged. Much remains to be understood regarding how insufficiency of E6-AP, the protein product of UBE3A, results in the observed neurodevelopmental deficits. Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling.
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PMID:Angelman syndrome: review of clinical and molecular aspects. 2487 91